The peony is a perennial bush that is prized for its hardiness. In fact, peonies need the winter chill in order to bloom in the spring. Most areas in Missouri experience an early spring and, because it gets hot so quickly, the peony blooming season is generally over by the first week of June. Some cultivars will bloom early, such as Buttercup, and a few might last through June in Missouri, such as Karl Rosenfield. Plant your peonies in the early fall (September is ideal) for spring blooms.
Choose an area of the garden that gets full sun. The peony prefers a full day of sun, but will tolerate some afternoon shade.
Dig a hole 18 inches deep and 18 inches wide. Add a half cup of fertilizer (10-6-4) to the bottom of the hole. Cover this with a 4-inch layer of compost.
Place the peony plant into the hole so that, when planted, the eyes (small, reddish buds) will be one to two inches below the surface of the soil. Fan out the roots and water well. Use your fingers to push the soil around the roots, patting it to remove any air pockets.
Backfill the hole completely, with a mixture of equal parts of compost and soil, and water again.
Fertilize the peony in the spring when the plant is 2 to 3 inches in height. Use a 5-10-10 granular fertilizer and work it into the soil around the base of the peony, being careful not to get any fertilizer on the roots.
Water deeply and regularly during the growing season when the weather is dry. Peony are somewhat drought tolerant, but during their first season it is best not to let them dry out too much.
Deadhead (cut or pinch off) old flowers to keep the plant from going to seed. Cut foliage back to 3 inches in the fall.